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S Sánchez

Publications and source records attributed to S Sánchez.

At least 19 recordsLinked to original sources
PubMed2006

Presence of Shiga toxin-producing E. coli O157:H7 in a survey of wild artiodactyls.

This study was carried out to evaluate the role of wild artiodactyls as reservoirs of Escherichia coli O157:H7 for livestock and humans. Retroanal mucosal swabs samples from 206 red deer (Cervus elaphus), 20 roe deer (Capreolus capreolus), 6 fallow deer (Dama dama) and 11 mouflon (Ovis musimon), collected during the hunting season (autumn-winter) in South-western Spain, were screened. Samples were pre-enriched in modified buffered peptone water, concentrated by an immunomagnetic separation technique and cultured onto selective cefixime tellurite sorbitol MacConkey agar. Polymerase chain reaction (PCR) was used to detect the presence of genes coding O157 and H7 antigens and the virulence factors verocytotoxin, intimin and enterohaemolysin. Three E. coli O157:H7 isolates were obtained from red deer (1.5%). Two of them showed inability to ferment sorbitol and lack of beta-d-glucuronidase (GUD) activity, however, the other strain investigated was an atypical sorbitol-fermenting E. coli O157:H7 with GUD(+) activity. This is the first report pointing to red deer as a reservoir of E. coli O157:H7 in Spain.

Adhesins, Bacterial↗
PubMed2006

Generation of aroma compounds from Ditaxis heterantha by Saccharomyces cerevisiae.

Ditaxis heterantha, a plant of the Euphorbiaceae family, is growing wild in the semiarid regions of Mexico. The seed endosperm contains yellow pigments (carotenoids). By high-pressure liquid chromatography the total pigment (TP) was separated into seven fractions: two of them, heterathin (F4) and ditaxin (F5), characterized as apocarotenoids, represent 80% of TP. Both molecules have double bonds, which seem to be the target for degradation and aroma formation. In this work, TP, F4, and F5 were supplied to nine cultures able to degrade lutein. From these strains, only one (identified as Saccharomyces cerevisiae) was able to produce aromas from either TP or F4. Using TP as substrate, the produced aromas were 4-oxo-isophorone (1), isophorone (2), cinnamic aldehyde (6), 3-hydroxy-beta-cyclocitral (7), safranal (8), geranyl (9), 3-oxo-alpha-ionone (10), 3-oxo-alpha-ionol (11), 3-oxo-7,8-dihydro-alpha-ionone (12), and eugenol (13). Of these aromas, only seven were produced from F4: (1), (2), (7), (8), (10), (11), and (12). In both cases, safranal was the main degradation product (30%). The enzymatic activity responsible for this effect was found in the cytosolic fraction and detected only when S. cerevisiae was grown in the presence of TP or F4.

Carotenoids↗
PubMed2006

Novel method for aroma recovery from the bioconversion of lutein to beta-ionone by Trichosporon asahii using a mesoporous silicate material.

In this work, we report on the synthesis and ability of the mesoporous material MCM-41 to adsorb the norisoprenoid beta-ionone. This compound, with a violet aroma note, can be produced from lutein by the yeast Trichosporon asahii through a bioconversion process. We found that beta-ionone inhibited the yeast growth and constrained aroma formation. Growth inhibition was overcome using silicate MCM-41 as sorbent device in a fermentation system that allowed product removal from the culture medium by headspace manipulation. Compared to a commercial silica gel, the mesoporous material exhibited a 4.5-fold higher beta-ionone adsorption. Contrasting to cultures without the sorbent device, the presence of MCM-41 allowed a marked increase (14-fold) in beta-ionone production. Our results suggested that confinement of the norisoprenoid into the sorbent material bypassed its toxicity which allowed a better beta-ionone production. This study represents the first report on the use of MCM-41 to recover an aroma produced by fermentation and therefore, a novel application for a mesoporous material.

Adsorption↗
PubMed2005

Prevalence, serotypes and virulence genes of Shiga toxin-producing Escherichia coli isolated from ovine and caprine milk and other dairy products in Spain.

The aim of this study was to determinate the prevalence, serotypes and virulence genes of Shiga toxin-producing Escherichia coli (STEC) strains isolated from different dairy products (DP) in Spain with the purpose of determining whether DP represent a potential source of STEC pathogenic for humans. A total of 502 DP were examined from 64 different ovine and caprine flocks and 6 dairy plants in Extremadura (Western Spain). Samples were collected monthly between March 2003 and June 2004 and included 360 unpasteurised milk obtained from the bulk tank, 103 fresh cheese curds and 39 cheeses. Samples obtained were examined for STEC using genotypic (PCR) methods. STEC strains were detected from 39 (10.8%) bulk tank, 4 (3.9%) fresh cheese curds and 2 (5%) cheese, whereas O157:H7 serotype were isolated from one (0.3%) bulk tank. A total of 9 STEC strains (O27:H18, O45:H38, O76:H19, O91:H28, O157:H7, ONT:H7, ONT:H9 and ONT:H21) were identified in this study. One of them, the serotype O27:H18, has not been reported previously as STEC. PCR showed that 3 strains carried stx1 genes, 5 possessed stx2 genes and 1 both stx1 and stx2. Whereas all STEC caprine isolates showed ehxA genes, only O157:H7 serotype showed eae virulence genes. The strain O157:H7 isolated possessed intimin type gamma1 and belonged to phage type 31. This study confirms that dairy product is an important reservoir of STEC pathogenic for humans.

Animals↗
PubMed2005

Trisomy of the short arm of chromosome 5 due to a de novo inversion and duplication (5)(p15.3 p13.3).

Partial trisomies of the short arm of chromosome 5 are uncommon. The first description was made by Lejeune et al., in 1964. It has been suggested that the critical region for 5p trisomy syndrome lies between 5p10 and 5p13. We report on a Mexican girl who developed severe mental retardation and generalized tonic clonic seizures at age 1 year. On physical examination at age 5 years, she had macrodolichocephaly, upslanted palpebral fissures, bilateral inner epicanthic folds, low nasal root, and malformed ears with posterior rotation which are clinical characteristics of 5p trisomy syndrome. The cytogenetic study with G bands and FISH with painting for chromosome 5 and with the cri-du-chat 5p15 unique sequence probe showed a duplication and inversion of 5p [46,XX, dup(5)(p15.3 p13.3)] which overlaps with the critical region for 5p trisomy syndrome. Our patient shares clinical characteristics with the patients described in the literature with involvement of this critical region. Both parents have normal karyotypes indicating the rearrangement is de novo. Only one patient has been reported in the literature with the same cytogenetic rearrangement as our patient, but this patient had a different phenotype. Since they only performed conventional cytogenetics and we performed FISH to confirm the diagnosis, the differences in the phenotypes could be explained by the presence of other genes involved in the rearrangement. The combined use of conventional and molecular cytogenetics in this case allows a more precise diagnosis and furthers knowledge in phenotype/genotype correlation.

Abnormalities, Multiple↗
PubMed2005

[Functional impairment in elderly patients hospitalised in an Internal Medicine unit].

To determine the functional status in elderly patients after a hospitalisation in an Internal Medicine unit. We prospectively studied patients aged 80 or above hospitalised in the Hospital Provincial de Ciudad Real in an Internal Medicine unit, between February and July, 2003. The functional status was determined by Barthel Index. We examined 206 patients (77.4%). They showed a previous Barthel Index of 70.9; one of 48.9 in the hospitalisation stage and one of 58.6 when discharged (p<0.001). We noticed a Barthel Index when discharged which was lower than the previous Barthel one in 73.8% patients. Hospitalisation implies a great functional impairment in the functional status elderly patients. It would be convenient, therefore, to identify the risk factors to be able to set some guidelines for a preventive model.

Activities of Daily Living↗
PubMed2004

A cAMP-activated pathway, including PKA and PI3K, regulates neuronal differentiation.

Neuronal differentiation is a complex process in which many different signalling pathways may be involved. An increase in the intracellular levels of cyclic AMP (cAMP) has been shown to induce neuronal differentiation and also to cooperate with NGF to induce PC12 neurite outgrowth in a Ras-dependent manner. However, the neuritogenic activities associated with cAMP are still not well understood. The purpose of this study was to investigate the potential neuritogenic activities mediated by cAMP. For this purpose, we used the human neuroblastoma cell line SH-SY5Y. These neuroblastoma cells respond to cAMP by forming neurite-like extensions. We tried to identify some essential pathways involved in the cAMP-induced neurite elongation of these cells. Our results indicated that PKA is transiently activated in this elongation model. When we blocked PKA activity, elongation did not take place. Similarly, PI3K also plays an essential role because when we blocked this kinase activity, there was no neurite elongation. Indeed, over-expression of the p110-catalytic subunit or an activating form of the p85-regulatory subunit (p65) is able to induce some degree of neurite extension. Moreover, our results showed that when elongation is initiated, PI3K is still essential for maintenance of the neuronal morphology, whereas PKA or MAPK (ERKs or p38) activation does not appear to be necessary during this process.

Cell Differentiation↗
PubMed2004

Orally administered tryptophan and experimental type 2 diabetes.

There is a link between diabetes and oxidative stress. Hyperglycaemia leads to free radical generation and alterations of endogenous antioxidants. Our aim is to study the effect of orally administered L-tryptophan (TRP), the melatonin precursor, an endogenous antioxidant, on circulating levels of glycaemia, insulin and melatonin, and on the superoxide dismutase and catalase antioxidant systems in non-diabetic (ND) and type 2 diabetic (n5-STZ) male Wistar rats. At 19:30 every day for 15 days, TRP (125 mg/kg body weight) was administered orally. At 09:00 every two days the glycaemia was measured and every day the intake of food and water was recorded. At the beginning and end of treatment (at 09:00; 21:00; 02:00) plasma insulin and melatonin levels were measured, and (at 09:00) the enzymatic activities of catalase and superoxide dismutase (SOD) in erythrocytes were also measured. Glycaemia values were greater (p < 0.01) in n5-STZ rats than in ND rats, while insulin levels were lower (p < 0.05) at all times studied and these parameters were not altered by the TRP administration. Melatonin levels at 02:00 were lower in n5-STZ than in ND rats (p < 0.05). The TRP administration did not modify the circulating melatonin levels in ND rats, but raised (p < 0.01) the levels at 02:00 in the treated n5-STZ group. In ND rats after TRP administration there was a decline in catalase activity (p < 0.05), while in n5-STZ rats there was a rise (p < 0.01) at the end of treatment. However, there were no significant changes in SOD activity. There was increased food intake (g/day) in the treated n5-STZ group (p < 0.01). In conclusion, the oral administration of TRP did not modify glycaemia or insulinaemia levels, but raised melatonin levels in diabetic rats at 02:00, lowered catalase activity in ND rats but raised it in n5-STZ rats, and increased food intake in n5-STZ rats.

Administration, Oral↗
PubMed2003

Dexamethasone decreases plasma levels of the prochiral fenbendazole and its chiral and achiral metabolites in sheep.

1. The effect of co-administration of either short- or long-acting formulations of DXM on hepatic function and the plasma pharmacokinetic behaviour of prochiral fenbendazole (FBZ) and its metabolites was evaluated in sheep. 2. Neither DXM treatment markedly affected any of the biochemical markers of hepatic function tested. In contrast, both formulations significantly modified the plasma pharmacokinetic behaviour of FBZ and its metabolites. 3. Plasma FBZ concentrations and the associated area under the time-concentration curves were significantly lower, although the plasma detection period was longer (72 versus 48 h) in the DXM pretreated animals compared with those given FBZ alone. 4. DXM also appeared to alter the pattern of FBZ absorption, possibly through effects on abomasal pH. The shape of the plasma concentration-time curves for oxfendazole (OFZ) and fenbendazole sulphone (FBZSO(2)) were similar to FBZ, raising the possibility that DXM treatment may have altered the liver biotransformation of the parent drug. 5. The concentrations of the (+) chiral metabolite of OFZ were significantly lower in DXM pretreated animals compared with those given FBZ alone. The trend was similar for the (-) antipode, although the differences between DXM pretreated and non-pretreated animals were not statistically significant.

Administration, Oral↗
PubMed2003

[Hepatitis C virus variability and interferon-mediated pathway inhibition].

The most important aim of this study was to describe the hypothetical relationship between the PePHD region variability (related to the synthesis of a cellular enzyme pseudosubstrate) of the hepatitis C virus and the response of patients to interferon therapy. This interaction could be a determining factor in the antiviral effect of interferon. All samples (from 24 patients with chronic hepatitis C infection) were analyzed using a previously described method based on RT-PCR and nested PCR mediated by single-strand conformation polymorphism assay (SSCP). The patients were divided into three groups with respect to the response to therapy: 8 patients with sustained response, 8 patients with transient response and 8 nonresponders. In all samples a low genetic heterogeneity pattern was detected, which was independent of other factors involved in the lack of response to treatment, such as age, sex or viral genotype. This genetic homogeneity is an indirect indication of the importance of the region on viral persistence. However, more studies are needed to evaluate the real role of this sequence on the interaction between cells and the virus.

Adult↗
PubMed2002

Analysis of Neisseria lactamica antigens putatively implicated in acquisition of natural immunity to Neisseria meningitidis.

Sera from healthy human volunteers, patients convalescent from meningococcal meningitis, and mice immunized with outer membrane proteins from Neisseria meningitidis and Neisseria lactamica strains were used to analyze and identify antigens cross-reactive to both neisserial species. All classes of meningococcal proteins except class 1 (PorA) and class 5 cross-reacted with N. lactamica proteins and two other proteins of 65 and 55 kDa (an iron-regulated protein). Results obtained with the mouse sera demonstrate that cross-reactive antibodies can be elicited by either N. meningitidis or N. lactamica. These results support the suggestion that N. lactamica contributes to the development of natural immunity against N. meningitidis during the first years of life. The use of vaccines containing proteins other than PorA could interfere in colonization of mucosal surfaces by N. lactamica, hampering the natural mechanisms of immunity acquisition in humans. Only convalescent sera reacted with the 55 and 65 kDa proteins, which suggests that they might be relevant for pathogenicity.

Animals↗
PubMed2002

In vitro induction of memory-driven responses against Neisseria meningitidis by priming with Neisseria lactamica.

Natural immunity against Neisseria meningitidis is acquired during childhood and youth through successive colonizations by commensal Neisseria, carrier N. meningitidis, and other bacterial genera sharing cross-reactive antigens with the meningococci. We have analyzed in mice the ability of Neisseria lactamica strains to induce immunological memory so that, upon a later contact with N. meningitidis, quickly raise protective responses against antigens that show cross-reactivity with meningococcal surface proteins. Sera obtained from mice immunized with N. lactamica and boosted with N. meningitidis were able to kill meningococci, with bactericidal activities variable depending on the immunizing strains used in the assays. Different mixtures of those sera resulted in higher killing activities, which agrees with the idea that successive colonizations by N. lactamica enhance the anti-meningococcal response. The existence of such outer membrane cross-reactive antigens has to be kept in mind when using outer membrane vesicle (OMV)-based anti-meningococcal vaccines because their use can affect colonization by N. lactamica and other species, hampering the natural mechanisms of acquisition of immunity to the meningococci, and leaving its ecological niche free for colonization by undesirable microorganisms.

Animals↗
PubMed2002

Role of prostaglandins and nitric oxide in gastric damage induced by metamizol in rats.

OBJECTIVE AND DESIGN: In addition to the depletion of prostaglandins (PGs), oxygen free radicals generation and nitrogen species haven been implicated in non-steroidal anti-inflammatory drugs (NSAIDs)-induced gastric injury. The aim of the present study was to examine changes in PGE2 generation and its relationship with proinflammatory parameters and nitric oxide (NO) production in the comparative pathogenesis of gastric injury induced by metamizol vs. diclofenac, NSAIDs that present different gastric tolerability and cyclooxygenase (COX) inhibition profiles. MATERIAL: Studies were performed in Wistar-Han rats. TREATMENTS: Metamizol (120, 500 and 1,000 mg/kg body weight) and diclofenac (50 mg/kg body weight) were given by oral administration. METHODS: Determinations were made of macroscopic and histological evaluation of gastric mucosal injury, gastric prostaglandin synthesis (PGE2 levels), myeloperoxidase activity (MPO), tumor necrosis factor-alpha levels (TNF-a), cyclic guanosine monophosphate (cGMP), nitric oxide synthase activity (NOS) and NOS mRNA expression. RESULTS: Metamizol, only at the highest doses assayed, provoked weak lesions in the gastric mucosa. To the contrary, diclofenac treatment presented the highest grade of lesion. All treatments decreased PGE2 gastric generation. Treatment of the animals with metamizol neither modified the MPO activity nor TNF-alpha levels. In contrast, statistically significant increases in both parameters were observed after diclofenac administration. cGMP levels were not influenced with diclofenac treatment, nevertheless metamizol reduced the nucleotide levels, which was accompanied by an inhibition of constitutive NOS (cNOS) activity without modifying the mRNA expression of the enzyme. CONCLUSIONS: In addition to inhibition of PG synthesis, damage induced by metamizol was associated with an inhibition of the NO/cGMP pathway and cNOS activity. In contrast, diclofenac-induced gastric damage was associated with an increase of the inflammatory response.

Animals↗
PubMed2002

Some comparative aspects of the pharmacokinetics of tylosin in buffaloes and cattle.

The pharmacokinetics of tylosin were compared in cattle (Bos taurus) and buffaloes (Bubalus bubalis). Six animals received each a single dose of 10 mg/kg of tylosin tartrate by the intramuscular route. The serum concentration (Cmax) and the volume of distribution (Vd) presented significant differences between the two species. Cmax was 0.40 +/- 0.046 microg/ml for buffaloes and 0.64 +/- 0.068 microg/ml for cattle. Vd was 1.91 +/- 0.12 L/kg and 1.33 +/- 0.09 L/kg for buffaloes and cattle, respectively. However, as the present study did not show considerable differences in the pharmacokinetics of tylosin in buffaloes and cattle, similar dosage regimes of this drug can be recommended for both species.

Animals↗
PubMed2002

Endometrial tissue concentrations of enrofloxacin after intrauterine administration to mares.

Endometritis in mares is a common cause of infertility. Conventional treatments of the disease have mostly been unsuccessful, so new therapeutic alternatives need to be investigated. This study evaluated the uterine disposition and plasma pharmacokinetic behaviour of a commercial formulation of enrofloxacin (EFX) given by the intrauterine (i.u.) route (2.5 mg/kg) in healthy mares. In order to evaluate the uterine inflammatory response, an initial histopathological study assessing polymorphonuclear cell infiltration was carried out in 20 mares over a 14-day period after treatment. In a second study, 6 healthy adult mares were used for the pharmacokinetic study. Samples of uterine tissue and plasma were collected from 0 to 24 h after the i.u. treatment with 5% EFX solution. Samples were analysed by conventional microbiological assay using an EFX-sensitive strain of Escherichia coli (ATCC 25922). There was a moderate but statistically nonsignificant inflammatory response following i.u. administration of either the formulation or the vehicle alone. Pharmacokinetic analysis of the uterine concentrations of EFX showed a slow and sustained depletion, with EFX remaining at concentrations above the MIC for 24 h after treatment. The area under the concentration-time curve obtained for the uterus suggested that EFX and its metabolites are specifically retained in the uterus, which is the target tissue for bacterial colonization. Neither study provided any evidence of EFX toxicity. In conclusion, these results are encouraging and suggest that EFX may be a useful local treatment in mares with bacterial endometritis.

Animals↗
PubMed2002

Plasma achiral and chiral pharmacokinetic behaviour of intravenous oxfendazole co-administered with piperonyl butoxide in sheep.

Co-administration of piperonyl butoxide (PB) potentiates fenbendazole (FBZ) in small ruminants. The resultant increase in bioavailability of FBZ and its metabolite oxfendazole (OFZ) has important implications for the efficacy of these drugs against benzimidazole (BZD)-resistant strains of Teladorsagia circumcincta. This study evaluated the racemic (achiral) and enantiomeric (chiral) plasma disposition kinetics of OFZ and its metabolites after the co-administration of PB and OFZ in sheep. Six 6-8-month-old, parasite-free, female Dorset sheep (30-40 kg) were used in a two-phase crossover experiment. In phase I, three sheep received 30 mg/kg PB orally, followed by a single intravenous (i.v.) injection of OFZ at 5 mg/kg. The other three animals were treated similarly except that 5 mL of water replaced PB. In phase 2, treatments for the two groups were reversed and were given 14 days after the initiation of phase I. Three analytes OFZ, FBZ and fenbendazole sulphone (FBZSO(2)) were recovered in plasma up to 48 h post-treatment in both experimental groups. Achiral and chiral pharmacokinetic (PK) profiles for OFZ, after the co-administration of PB, were characterized by a significantly greater area under the concentration--time curve (AUC) and a longer mean residence time (MRT). Chiral OFZ distribution ratios were comparable in both treatment groups. Piperonyl butoxide treatment markedly influenced the plasma PK profiles for FBZ and FBZSO(2) following OFZ administration. Production of FBZ was enhanced as reflected by increased (> 60%) AUC, delayed T(max) and a significantly delayed (> 45%) elimination (t(1/2)(el)). Although AUC values for FBZSO(2) were not significantly different between groups, this metabolite was depleted more slowly from plasma (t(1/2)(el) > 60% and MRT > 42%) following PB treatment. This study demonstrated that PB co-administration is associated with an inhibition of OFZ biotransformation, as evidenced by the significantly higher plasma concentrations of OFZ and FBZ, and this could have important implications in terms of anti-parasite therapy against BZD-resistant parasite strains.

Administration, Oral↗